Sugar in Concrete:
- Cement and Concrete are the foremost paramount engineering materials.
- Tyrannical weather conditions play indispensable roles on the traits of concrete. Hence, admixtures are required to sustain standard conditions. Continuous change in weather conditions results in a change of initial setting time of concrete.
- Hence, Retarders and Accelerators are required to increase and diminish the initial setting time of concrete respectively. e.g. Retarder– sugar and gypsum etc. & Accelerator- salt (cacl2) etc.
- Retarders are admixtures which stretch the ‘Hydration Induction Period’.
- Sugar delays the setting of cement at the construction site & it’s affordable and promptly obtainable.
Distinction Between Cement and Concrete:
- Concrete is basically a blend of aggregates (gravel & stone-dust) and paste (water & portland cement). Concrete gets brawny as it grows older over time.
- Cement comprises from 10-15 % of the concrete blend, by volume.
What Is the Effect of Sugar on Setting Time of Concrete?
Little dosage of 0.06% of sugar (white crystalline solid) will interlude the initial setting time by about 45 minutes 45 seconds.
Usually eight completely different percentage of sugar admixture is taken. They are as follows- 0.0, 0.02, 0.04, 0.06, 0.08, 0.1, 0.2 & 1.0 by weight of cement.
It’s tested that utilization of >1% of sugar concentration might utterly impede the tactic of concrete setting for several days.
Apart from that, the compressive strength of the concrete is at 3, 7, and 21 days.
- Trehalose – These molecules don’t affect concrete setting time.
- Lactose – These molecules may be a moderate concrete retardant.
- Sucrose – This molecule is one amongst the most effective retardants and possibly the foremost effective Concrete Retardant.
- Skimmed Milk Powder –These molecules encompass a retarding effect on the setting time of concrete due to the sugar present in it.
Sugar as a Concrete Surface Retarder:
- Sugar is utilized as a retarder for a concrete mixture.
- Retarders interlude the initial setting time of the concrete.
- They’re generally utilized in the new atmospheric condition to counter the rapid coagulation because of high temperatures.
Sugar to Concrete Ratio:
- The sugar-concrete blend endorsed for this procedure is 1:1.2 & 2:2.78 with a water-cement ratio of 0.45.
- All the specimens are watered for 28 days.
- The compressive strength specimens are of dimension 150 x 150 x 150 mm.
- After 28 days the maximum compressive strength for 0.06% of sugar and water-cement ratio is 0.36, 0.45, 0.50 are 48.88 N/mm2, 44.44 N/mm2, 40.14 N/mm2 respectively.
What Is Going to Happen If We Add Sugar in Concrete?
Based on Studies & Research, the study concludes that:
- Sugar delays the setting time of cement (near about 1.33 hours at a dosage of 0.06% by weight of cement). On account of its action with concrete, sugar is rather considered as a delayed accelerator in lieu of a retarder.
- Use of sugar as an admixture doesn’t affect the workability (Durability, Absorption & Shrinkage properties) in concrete.
Recommendations of Sugar in Concrete:
- Sugar is ought to be utilized as a retarder but if it’s employed in imprudent quantity, it reverses its properties.
- The quantity of the sugar must be precisely measured during the production process. Sugar content of 0.06% by weight of cement can ameliorate the compressive strength of concrete (by 3.23% at 28 days) and delay initial setting time by 1.33 hours (80 minutes).
- The time delay of 3 & 7 days, in case of addition of sugar, safe-guards cold joints, by diminishing early setting of cement in tyrannical weather conditions.
- The addition of OPC (Ordinary Portland Cement) offers retardation of 4hrs. Even some sorts of salts act an identical purpose.
How Does Sugar in Concrete Work?
The foremost notable theories are as follows:-
Theory 1: Formation of Sugar Coat –
- In the process of setting concrete water requires to react with cement but, sugar-concrete combination inhibits this reaction by forming a canopy around the cement particles.
Theory 2: Formation of Insoluble Complexes –
- On incorporation of sugar to concrete by this procedure, the concentration of Al & Ca gets diminished, as sugar forms complexes with these elements. Therefore, the reaction between Al, Ca, water is inhibited.
Theory 3: Glucose Catalytic Principle –
- Since the surface of sugar has robust polarity it ends up in solid-liquid adsorption thus it hinders the crystal contact and tri-calcium silicate hydrate reaction.
To Adjust the Setting Time of Cement Which Product Is Added with Cement?
Setting time of cement increases by adding gypsum, salt, sodium oxide, and calcium sulfate.
- Gypsum may be a mineral and is hydrated salt in chemical form.
- Gypsum plays an awfully vital role in manipulating the solidification of the cement.
- Gypsum is incorporated to regulate the “setting of cement”. Otherwise, the cement will set instantly after mixing of water leaving barely any time for concreting process.
Initial & Final Setting Time for Sugar in Concrete:
Initial Setting Time for Sugar in Concrete.
- Initial Time of cement is the time required by the cement for its early setting. Usually the initial setting time of cement is 30min.
Final Setting Time for Sugar in Concrete.
- Final Time is the time span between the blending of the water & the time when the needle just makes the impression on the surface of the cement (but do not penetrate into it). Usually the final setting time of cement is 10-12 hrs.
Why Gypsum Is Added in Cement for Sugar in Concrete?
- Tri-calcium aluminate (C3A), is the usually most reactive among the four minerals available(which are responsible for coagulation) in cement.
- The increase of C3A can act as a positive catalyst in the setting and coagulation rate of cement, a huge amount of heat is radiated. Hence, the reaction of C3A with water occurs rapidly and is manipulated by adding gypsum during the production procedure.
- Gypsum (crystallized CaSO4) is incorporated to cement along with water to manipulate the setting process. Gypsum content of cement is usually expressed in terms of its sulfate content.
- When cement is hydrated, gypsum reacts with C3A quickly to come up with calcium sulfoaluminate hydrate which precipitates and forms a film on the cement particles which hinders the hydration of C3